c1af31f75a
NCPU was 16, under what a desktop has today. 64 costs 48 more TSS I/O bitmaps and scheduler stacks, about 800 KB of BSS. Past 254 the APIC would need x2APIC mode, which is a separate change. With more than 16 there were two other ceilings. sched_getaffinity wrote "CPU 0" and returned 0, and musl clears every byte past the count returned -- so the mask came back empty and nproc, make -j and sysconf(_SC_NPROCESSORS_ONLN) all said 1, on any machine. It returns the mask of processors that started, and its size, now. And /proc rendered every file into 2 KB, which /proc/cpuinfo ran out of at the eighteenth processor without a word; /proc/pci, /proc/interrupts and /proc/mounts were each one bigger machine from the same cut. There is one 64 KB buffer for it now behind a sleeplock, since there is no allocator for contiguous pages, and the generators that write raw are given the real capacity instead of a constant. Checked under QEMU with -smp 24: nproc 24, /proc/cpuinfo whole. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
71 lines
3.7 KiB
C
71 lines
3.7 KiB
C
#pragma once
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// The timer interrupt rate the kernel is built around. Everything that turns
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// ticks into a duration divides by this. It used to be the literal 100 written
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// out at each site, which made it look like a fact about the hardware; it is
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// not. It is a target, and kernel/arch/x86_64/lapic.c calibrates the LAPIC
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// timer against the PIT to actually hit it.
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#define HZ 100 // timer interrupts per second
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// The tick rate the *user-space ABI* is defined in, which is a different thing
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// from HZ and must not follow it. glibc and musl both answer sysconf(_SC_CLK_TCK)
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// with a hardcoded 100, so times() and /proc/stat are read as hundredths of a
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// second no matter what the kernel's internal rate is. Linux calls this USER_HZ
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// and scales at the syscall boundary; so does SchOS, in the two places below.
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#define USER_HZ 100
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// Converting a POSIX timespec/timeval into ticks. These used to appear as the
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// bare literals 10000000 and 10000 at each call site, where they looked like
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// magic numbers rather than what they are: the length of one tick, expressed
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// in the units the caller happens to be using.
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#define NSEC_PER_TICK (1000000000 / HZ)
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#define USEC_PER_TICK (1000000 / HZ)
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#define MSEC_PER_TICK (1000 / HZ)
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#define NPROC 128 // maximum number of processes
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#define KSTACKSIZE 8192 // per-process kernel stack; see kstacks[] in proc.c
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#define KSTACK_CANARY 0xDEADC0DEDEADC0DEULL // sentinel at kstack[0], see kstack_check_canary()
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#define NCPU 64 // maximum number of CPUs
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#define NOFILE 128 // open files per process
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#define NFILE 512 // open files per system
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#define NINODE 200 // maximum number of active i-nodes
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#define NDEV 13 // maximum major device number
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#define RAMDISK_DEV 2 // memory-backed block device (kernel/dev/ramdisk.c)
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#define USBDISK_DEV 3 // USB mass storage (kernel/drivers/usb_storage.c)
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// Device the root filesystem is mounted from. Building with RAMROOT=1 defines
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// RAMDISK_ROOT and boots from the SCHFS image linked into the kernel instead
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// of the IDE disk, leaving the physical disk free to be reformatted from a
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// running system. See kernel/dev/ramdisk.c.
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#ifdef RAMDISK_ROOT
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#define ROOTDEV RAMDISK_DEV
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#else
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#define ROOTDEV 1 // device number of file system root disk
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#endif
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// exec's limits, Linux's: ARG_MAX bytes of argument and environment strings
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// and their pointers together, and no one string over ARG_STRLEN_MAX (Linux's
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// MAX_ARG_STRLEN). There is no limit on the count beyond that.
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#define ARG_MAX (2 * 1024 * 1024)
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#define ARG_STRLEN_MAX (128 * 1024)
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#define MAXPATH 128 // max path
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#define MAXOPBLOCKS 30 // max # of blocks any FS op writes
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#define LOGSIZE (MAXOPBLOCKS*3) // max data blocks in on-disk log
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// Disk block cache, in blocks. 256 * BSIZE = 1 MB.
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//
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// Was MAXOPBLOCKS*3 = 90 blocks, and at the old 1 KB BSIZE that is a 90 KB
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// cache -- smaller than the toybox binary that every single command execs. So
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// nothing was ever still resident on the next command and each one paid the
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// full read again. 1 MB holds toybox with room to spare, which is what makes
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// the *second* command fast rather than just the first.
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//
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// Sized rather than maximised: these are statically allocated in bio.c, so
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// this is memory the system always spends. 1 MB is affordable on a machine
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// with tens of megabytes; 8 MB would not be.
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#define NBUF 256
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#define FSSIZE 150000 // size of file system in blocks
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// Network interfaces the stack will attach. Two is already an ordinary machine
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// -- a laptop with Ethernet plus a virtual adapter -- and each one costs a
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// struct netif, so the limit is about keeping a fixed array honest rather than
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// about memory.
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#define NETIF_MAX 4
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